1. Field of the Invention
The present invention relates to an ultra high frequency (UHF) radio frequency identification (RFID) tag and a method of manufacturing the same.
2. Description of the Related Art
An RFID tag includes circuitry (e.g., a microchip) for storing various data and an antenna that is connected to the circuitry for inputting the data or transmitting the stored data to a reader. The RFID tag is used with the reader that receives a signal transmitted from the antenna (i.e., backscatter) and sends the signal to a dedicated computer to enable an operator to obtain and analyze the RFID tag's data.
Various data stored on the RFID tag is read via wireless communication between the RFID tag and the reader in a process known in the art as “interrogation.” The RFID tag is attached to individual items, such as products, cargos, materials, marketable securities, animals and plants, to improve efficiencies of production, distribution and marketing.
FIG. 1 is a schematic view depicting a construction of a conventional RFID tag 11.
In RFID tags, the structure and shape of the antenna are varied depending upon a used frequency band or maximum wireless identification (i.e., read) range to be required.
FIG. 1 shows an example RFID tag 11 that operates in the high frequency (HF) range of about 13.56 MHz. The RFID tag 11 includes a rectangular substrate 13, a conductive film 21 that is secured to a center of the substrate 13, a chip 19 that is mounted onto an upper surface of the conductive film 21 and electrically connected to the conductive film 21, and a loop antenna 15 surrounding the chip 19 and having both ends connected to the chip 19 via the conductive film 21. One end of the loop antenna 15 is directly connected to the conductive film 21, and the other end is indirectly connected to the conductive film 21 via a connection 17.
The antenna 15 and the chip 19 compose a closed circuit that operates in response to an external frequency (e.g., an electromagnetic field).
Since the antenna 15 occupies a significant area on the surface of the substrate 13 of the conventional RFID tag 11, the entire area of the tag 11 cannot be narrowed, which limits potential applications of the tag 11. Moreover, the illustrated antenna 15 may easily become damaged or scratched resulting in a short or open circuit. Of course, if any one portion of the antenna 15 is damaged, the tag 11 is rendered useless.
For a conventional RFID tag operating at ultra high frequency (UHF), the UHF RFID tag is previously prepared and is then attached to a target portion of the object through a separate process. In this case, the RFID tag may become damaged in the process of preparing the RFID tag (e.g., peeling off a backing from an adhesive layer) or attaching the RFID tag to the object.
Also, the foregoing conventional UHF RFID tag, which has a lead frame-type (i.e., printed circuit-type) antenna, is made by a process of coating a lower end of the lead frame antenna with an additional insulation thin film, attaching and molding the antenna to a chip. Therefore, the manufacturing process is complicated.